1. Field of the Invention
The present invention relates generally to a Multiple-Input Multiple-Output (MIMO) communication system, and more particularly, to a method applied in a receiver of a MIMO system for MIMO detection in an existing or future information transmission system.
2. Description of the Related Art
Conventionally, channels are first estimated when a receiver in the MIMO system detects a signal from a transmitting counterpart. According to the estimated channels and using a method of Minimum Mean Squared Error-Ordered Successive Interference Cancellation (MMSE-OSIC) or Minimum Mean Squared Error-Ordered Successive Interference Cancellation—Multiple Candidates (MMSE-OSIC2), data is detected separately for channels, i.e., one channel is independent of another channel.
A 2×4 MIMO detection process may be used as an example, in which the transmitted data, ×1 and ×2, are to be detected. According to conventional detection methods, it is necessary to detect ×1, and then to estimate ×2 according to the detection result of ×1. The difference between MMSE-OSIC and MMSE-OSIC2 lies in that only one possibility is decided when implementing MMSE-OSIC detection of ×1, while several candidates are decided when implementing MMSE-OSIC2 detection of ×1. With the increasing number of candidates, the detection performance improves, however the detection complexity also increases accordingly. When the number of candidates equals 1, the two detection methods are exactly the same.
The term, a correlation time, used herein refers to a specific time interval, within which amplitudes of two arrived signals are highly correlated. The term, a correlation bandwidth, refers to a specific frequency range, within which the amplitudes of two frequency components are highly correlated.
The existing techniques are disadvantageous in that property of channel correlation is not used in the data detection, because data detection in the existing method is implemented separately for channels. In an environment having noise bursts, it is possible for great burst of estimation deviation to happens randomly. In this case, if signal detection is implemented to the channel with great estimation deviation, a great error occurs or the Bit Error Rate (BER) increases in signal decision.
The existing technique is also disadvantageous in that in order to obtain specific BER performance, a hardware resource for the decoding method, which is directly proportional to the number of candidates in MMSE-OSIC2, is required.